Cucumber (Cucumis sativus) is a major vegetable crop worldwide and among the most important crop species in the Cucurbitaceae family. They are eaten as a vegetable, either fresh, cooked, or made into pickled cucumbers. The more than 100 varieties produce oblong fruits ranging in size from small pickling to long Dutch cucumbers and from can range in color from white, yellow or brown, to a dark green for the cultivated varieties. Cucumbers are generally considered less nutritious than most other vegetables, the fresh cucumber is a good source of vitamins A, B1, B5, B6, B9, C, and K, and minerals. Most greenhouse varieties produce fruit without pollination and are gynoecious with respect to flowering, (i.e. produce predominantly female flowers).
Fusarium stem and root rot of greenhouse cucumber is predominantly caused by Fusarium oxysporum f. sp. radicis cucumerinum (Forc). An additional causal agent of Fusarium stem and root rot is Fusarium oxysporum f. sp. cucumerinum (Foc). Chemical control of infection by Fusarium is performed by substances such as formaline. It is generally understood that formaline will be banned as pesticide.
WO02062130 describes methods for the production of cucumber plants that are genetically resistant to Fusarium oxysporum f. sp. radicis-cucumerinum (Forc). The method essentially comprises crossing a Forc-resistant cucumber plant designated C566 with a cucumber plant displaying desirable phenotypic characteristics, or using a plant of designation C566 as a rootstock. Using this accession as a resistance source in breeding in the absence of molecular tools such as markers imposes an undue burden to the breeding program and is virtually unfeasible. Crosses of C566 with susceptible lines resulted in nearly susceptible F1 hybrids. The BC1 generation with the elite parent was completely susceptible. These observations are indicative of a recessive mode of inheritance and poor heritability of resistance to Fusarium derived from C566. In addition, it is not known whether plants of designation C566 exhibit resistance to Fusarium oxysporum f. sp. cucumerinum (Foc). These attributes strongly reduce the attractiveness of C566 as a source for resistance to Fusarium in cucumber breeding programs. Hence, there is a need for plants that can serve as source for commercial cucumber varieties that can provide resistance to both Forc and Foc. In addition, it is preferred that such plants can be used to produce progeny plants that exhibit a high level of resistance at high frequency, and that elite inbred lines can be produced as parents for producing commercial seed lots that provide resistant progeny with high reproducibility.